This invention relates to coaters for applying a fluid coating to a traveling web such as paper. More particularly, this invention relates to an apparatus for adjustably defining the width of the coating application to the traveling web. Still more particularly, this invention relates to a coater end seal wherein an elastomeric seal is adjustably mounted in place by virtue of its being attached to a case which is magnetically secured to the coating apparatus.
In certain types of coaters wherein an excess amount of fluidized coating material is brought into contact with a traveling web to be coated by the material, the web is supported by a backing roll while the fluidized coating material is metered onto the web by a blade which is biased against the web over the backing roll downstream of the point where the coating material is applied to the web. The backing roll has a face width which is greater than the width of the web to be coated so that the coating blade is supported for its entire length over the face of the backing roll. This type of configuration also requires a seal at either end of the coating blade to prevent migration of the coating material around the ends of the coating blade. Such leakage of the coating material is not only wasteful, but if the coating material gets around the edges of the web, it could undesirably coat the edge portion of the other side of the web, thus requiring subsequent trimming of the web to remove the edge portion which was undesirably coated.
This end seal at either edge of the coater blade is made of an elastomeric material in order to provide a conforming seal against the wiper which, in turn, is pressed against the edge of the web being coated.
Heretofore, this seal was attached to the coater blade by means of double-faced tape. This mounting arrangement works adequately, but it has two serious drawbacks. First, once the seal is installed, the tape will not permit any sliding movement and it cannot otherwise be easily moved to adjust for changes in the width of the web being coated or changes in the position of the seal against the edge of the web. Secondly, once the seal has been installed, it cannot be replaced without shutting down the coater and cleaning and drying all surfaces contacted by the tape because the coating material has previously covered all exposed areas of the blade as well as all exposed areas of adjacent apparatus. Thus, the tape cannot be reapplied to a dry area at any other location. This seriously limits both the effective life of the seal and also requires costly downtime in order to clean the blade to provide a dry spot to allow the tape to secure the seal against the blade.